Customizing Statistics Publishing

The following needs to be done in order to implement a custom statistics observer.

To disable operation of publishing statistics via the EI Analytics server, add the following configuration in the <EI_HOME>/conf/carbon.xml file to true as shown below.
```
<MediationFlowStatisticConfig>
<AnalyticPublishingDisable>true</AnalyticPublishingDisable>
</MediationFlowStatisticConfig>
```
This is useful when you want to collect statistics using a product other than EI Analytics. In such scenarios, preventing the EI Analytics server from publishing statistics allows you to avoid incurring an unnecessary system overhead.
Create the JAR file with the that contains the required statistics observer implementation, and copy it to the <EI_HOME>/lib directory. This implementation should have the following.
- The org.wso2.carbon.das.messageflow.data.publisher.observer.MessageFlowObserver interface.
- If the observer is tenant aware, it should also implement org.wso2.carbon.das.messageflow.data.publisher.observer.TenantInformation.

Add all the observers as a comma separated list in the <EI_HOME>/conf/carbon.xml file as shown in the example below.

<MediationFlowStatisticConfig>
<Observers>
    org.wso2.custom.Observer1,org.wso2.custom.Observer2
</Observers>
</MediationFlowStatisticConfig>